pH and Living Systems Lab
pH and Living Systems
I. Purpose: To observe the effects of pH change on an organic molecule.
II. Materials: pH paper Droppers Ammonia
Beakers (50ml) Paper towels water
Glass stirring rods lemon juice forceps
III. Procedure:
Part 1:
Initial pH testing
1) First use the wide range pH paper to test the pH of the liquids given.
2) When you test with the wide range paper first (which reads pH from 0-13) be sure to read the pH paper using the correct chart.
3) Later, after you’re done testing with the wide ranged paper be sure to retest the pH level with the narrow ranged paper.
4) Complete both tests for:
Water, Milk, Ammonia, and Lemon juice
Part II- Testing the effect of pH change on an organic molecule.
1) Get a 50ml beaker and droppers. Count out 100 drops of milk into the beaker.
2) Retest Milk with the appropriate marrow range pH paper
3) Record data for the narrow range reading on your table. Write observations like what do you see, or what do you smell?
4) Add one drop of lemon juice using a clean dropper. Agitate the liquid. Read the pH and record observations
5) Repeat the step above until an observation change is noted. Be sure to ask if it is an appropriate time to stop.
6) Remember to use the same 100 drops of milk throughout the experiment
7) Repeat the entire process using a new 100 drops of milk and ammonia this time
Liquid
Wide Range pH
Narrow Range pH
Water
Lemon Juice
Milk
Ammonia
Analysis: In this lab, one observed that acids and bases affect the pH of milk differently from one another. For example, the lemon juice gave the milk a lower pH because of the acidity of the lemon juice. That’s why the milk curdled. Another example, when ammonia was added to milk in part II of the lab, the pH level increased greatly. pH is the symbol for the logarithm of the reciprocal of hydrogen ion concentration in
I. Purpose: To observe the effects of pH change on an organic molecule.
II. Materials: pH paper Droppers Ammonia
Beakers (50ml) Paper towels water
Glass stirring rods lemon juice forceps
III. Procedure:
Part 1:
Initial pH testing
1) First use the wide range pH paper to test the pH of the liquids given.
2) When you test with the wide range paper first (which reads pH from 0-13) be sure to read the pH paper using the correct chart.
3) Later, after you’re done testing with the wide ranged paper be sure to retest the pH level with the narrow ranged paper.
4) Complete both tests for:
Water, Milk, Ammonia, and Lemon juice
Part II- Testing the effect of pH change on an organic molecule.
1) Get a 50ml beaker and droppers. Count out 100 drops of milk into the beaker.
2) Retest Milk with the appropriate marrow range pH paper
3) Record data for the narrow range reading on your table. Write observations like what do you see, or what do you smell?
4) Add one drop of lemon juice using a clean dropper. Agitate the liquid. Read the pH and record observations
5) Repeat the step above until an observation change is noted. Be sure to ask if it is an appropriate time to stop.
6) Remember to use the same 100 drops of milk throughout the experiment
7) Repeat the entire process using a new 100 drops of milk and ammonia this time
Liquid
Wide Range pH
Narrow Range pH
Water
Lemon Juice
Milk
Ammonia
Analysis: In this lab, one observed that acids and bases affect the pH of milk differently from one another. For example, the lemon juice gave the milk a lower pH because of the acidity of the lemon juice. That’s why the milk curdled. Another example, when ammonia was added to milk in part II of the lab, the pH level increased greatly. pH is the symbol for the logarithm of the reciprocal of hydrogen ion concentration in